Ay multiple gun rotatable television projector head for 360 degree displ

ABSTRACT

A rotating television projection tube includes multiple projection guns within a single envelope and thereby provides multiple projection beams. Each beam repeatedly produces a single stroke scan line which, when projected vertically on a 360* projection screen, and when moved horizontally by rotating the tube causes a continuous television raster to be generated through 360*.

United States Patent [1 1 Herndon MULTIPLE GUN ROTATABLE TELEVISIONPROJECTOR HEAD FOR 360 DEGREE DISPLAY [7 5] lnventor: John W. Herndon,Orlando, Fla.

[22] Filed: July 11, 1972 [21] Appl. No.: 270,756

2 [111 3,758,714 [451 Sept. 11,1973

3,542,948 ll/i970 Wolff l78/6 Primary" ExaminerRichard MurrayAttorney-Richard S. Sciascia et al.

- [57] ABSTRACT A rotating television projection tube includes multipleprojection guns within a single envelope and thereby [52] US. Cl l78/7.5D, l78/DIG. 35, l78/6.8,

178/73 provides multiple pro ection beams. Each beam repeat- 51 Int. Cl..1104" 3/28 edly ProduceS a Single Stroke Scan line which, when [58]Field of Search l78/7.5 R,'7.5 o, P i vertically Projection Screen, and178/7], 68 6 DIG 35 738 when moved horizontally by rotating the tubecauses a continuous television raster tobe generated through [56]References Cited UNITED STATES PATENTS V 7 3,432,219 3/1969 Shenker etal l78/7.88 7 Claims, 2 Drawing Figures .lmmmmll Patented Se t. 11, 19732 Sheets-Sheet 1 Patented Se pt. 11,1913 i Y 3,758,714-

2 Sheets-Sheet 2 BACKGROUND OF THE INVENTION This invention relates to360 television displays and more particularly to an'improved multiplebeam, rotatable projection head therefor. In the field of projectiontelevision a problem that has presented various difficulties in solutionis that of providing adequate picture brightness for 360 displays. Astandard means uses a plurality of fixed projectors with the edges oftheir rasters matched as closely as possible on the screen. Difficultiesin obtaining registry between the rasters has prevented this from beinga satisfactory technique. Another technique is to mount severalprojectors on a common shaft and by single stroke vertical line scanningand by rotating the projector assembly a satisfactory 360 continuousraster is produced. This system, exemplified by U. S. Pat. No.3,542,948, has the problem of considerable rotating mass. Still anothertech nique is to utilize multiple fixed projectors operating in thesingle stroke vertical scan mode and mediate the beams with a speciallycontoured optical reflector. This arrangement, disclosed in my'copendingUS. Pat. application Ser. No. 245,415, filed Apr. 19, 1972, requires thefabrication of 'a highly complex optical element.

SUMMARY OF THE INVENTION With the foregoing in mind, it is a principalobject of this invention to provide improved projection head for use in360 television projection of a high brightness continuous rasterdisplay.

Another object of this invention is to provide such a projection headwhich contains, within a common envelope, a plurality of cathode raytube electron guns located around a common vertical axis, and aimeddownwardly so that when operated their single stroke scans illuminate aphosphor coated faceplate.

Still another object is to provide, as part of the projection head, aninternal rotatable faceplate on which a suitable phosphor is applied,rotation of the faceplate serving to avoid damage to the phosphor byrepeated single stroke scanning.

Yet another object is to construct the common envelope of suitablematerials so that said envelope may be evacuated, sealed, and mounted ina bearing assembly such that the envelope may be freely rotated by adrive motor while light produced by the illuminated phosphor passesthrough an optically clear faceplate portion for projection.

Another object is to provide prisms or mirrorsbelow the said envelopefaceplate such that the light beams from the illuminated phosphor arereflected outward radially from the tube assembly, with the beams fromthe prisms being mediated by suitable optical lens means affixed to therotating tube assembly.

The invention may be further said-to reside in certain arrangements ofoptical, electrical, electronic and mechanical parts whereby theforegoing objects and advantages are achieved, as well as others whichwill become apparent from the following description of a presentlypreferred embodiment when read in conjunction with the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a view, partly in sectionand partly in elevation, illustrating a 360 panoramic display televisionsystem including a rotating gun projection head embodying the invention;and

FIG. 2 is an enlarged view, partly in vertical section, of theprojection head of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT supported by brackets 12 fromthe ceiling 14 of a structure in which it is to be used, and is locatedon the central axis of a spherically curved projection screen S. Thescreen S is supported by legs 16 on a floor 18. The screen may be usedto display T.V. images projected by the head 10 for any purpose such asto provide visual cues to a pilot trainee Tin a cockpit simulator 20.The projection head 10 about'to be described provides a continuous 360raster on the screen S drawn by repetitive, vertically 'moving scanningbeam action.

Referring now toFIG. 2, the projection head 10 comprises a stationaryframe 30 having a depending cylindrical skirt portion 30a. Rotatablymounted in the skirt portion 30a is a generally cylindrical, evacuatedenvelope 32 conveniently formed of glass and having a transparentfaceplate 32a recessed into the lower end thereof. The envelope 32 has ashaft 34 extending axially from the upper portion thereof and carried ina suitable low friction bearing means 36 in the frame 30. The shaft 34is drivingly engaged by the shaft 38 of an electrical motor 40 which ismounted by a bracket 42 on the frame 30. The envelope 32 is furthersupported for rotation within the frame 30 by anti-friction bearingmeans 44 received in the lower edge of the frame skirt portion 30a. Theshaft 34 carries a slip ring assembly 50 including apluralityof sliprings 50a 50h which cooperate with brushes 52a 52h extending inwardlyfrom insulative brush carrier means 54. The brushes and slip rings serveto provide electrical connections to various components within therotating envelope 32. A plurality of electron beam forming guns aresupported within the envelope, two of which are shown at 560 and 56b,;byinsulating support members 60 and 62. The electron guns 56a and 56b, andothers if more than two are used, are aligned with their principal axesparallel to and equidistant from the central axis of the cylindricalenvelope 32. These electron guns, which are themselves of conventionalconstruction incorporating electrostatic deflection means, direct theirelectron beams 64 to impinge on a phosphor coating or layer 66 on arotatable transparent disc 68.

The plate 68 is supported for rotation about the central axis of theenvelope 32 by. a shaft 70 extending from reduction gearing 72 drivenbyan electric motor '74. The shaft 70 has its end remote from the motorand gearing journalled in bearing means 76 carried by the faceplate 320,while the motor and gearing are-supported within the envelope bysuitable spider means 80. The purpose of the rotating disc 68 is toprevent burning of the phosphor coating 66 because of the repeatedsingle line sweep characteristic of operation of the projection head.

In order to provide the necessary high voltage field for operation ofthe electron guns, the inner surface of the envelope has a portioncoated with a conductive metallic layer 80 which is adapted to besuitably charged as an anode. Thus, the layer 80 is connected by aconductor 82 to a slip ring 84 on the surface of the envelope 32. Theslip ring 84 cooperates with a brush 86 mounted in a suitably insulatedmanner on the frame skirt 30a and supplied with high voltage power via aconductor 88.

Mounted adjacent the underside of the faceplate 32a of the envelope 32are a plurality of beam reflectors in the form of prisms, two of whichare shown at 90a and 90b. While only two such prisms are shown, thenumber will correspond to the number of electron guns embodied in theprojection head 10.

The prisms 90a, 90b are arranged to produce redirection of light energy92 emanating from the phosphor coating 66 when activated by the electronbeams 64. This redirection of the light energy 92 directs it throughprojection lens means 96a and 96b which form, from the light energy,scanning beams 98a and 98b which are focused at the screen S. j

In operation of the system the electron beams 64a, 64b are caused totrace single line scans on the phosphor coating 66 such that thescanning beams 98a, 98b draw substantially vertical traces on the screenS. The motor 40 drives the envelope 32 at such a rate that apredetermined number of such vertical line traces are drawn by the beams98a, 98b on the screen S during each revolution of the envelope, therebycreating a 360, continuous raster on the screen. The timing of thedeflections of the beams 64a, 64b is preferably such that the beams 98a,98b draw interlaced fields. The electron beams 64a, 64b, and hence thescreen scanning beams 98a, 98b are modulated by television video signalsderived from television camera means operating on the same principles asthe projection head 10. That is, a rotating television camera headhaving a plurality of individual cameras corresponding to the individualelectron guns 56a, 56b may be used to provide the desired televisionvideo signals either directly in real time, or for later playback fromrecordings.

While only two electron guns and a corresponding number of reflectionmeans and projection lens means are shown for clarity, a greater numberof such elements, say six of each, would be advantageous in achieving ahigh degree of image brightness in the display generated.

Obviously many other modifications and variations of the presentinvention are possible in the light of the above teachings. It istherefore to be understood that within the scope of the appended claimsthe invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A television projection head for providing 360 panoramic projectionon a surrounding projection screen, said head comprising:

frame means;

an envelope mounted for rotation with respect to said frame means abouta vertical axis;

drive means for rotating said envelope;

a plurality of electron guns disposed within said envelope in equispacedrelation about said axis and with their principal axis parallel thereto;

phosphor coated screen means disposed in the path of electron beams fromsaid guns;

a plurality of reflecting means, each disposed to reflect radiallyoutwardly light emitted by said phosphor coated screen means whenscanned by the electron beam from a respective one of said guns; and

a plurality of projection lens means, each associated with one of saidreflecting means, for focusing said reflected light upon a screenwhereby radial single line scans of said phosphor coated screen means byeach of said guns will produce a raster of substantially vertical linescans on said projection screen as said head is rotated by said drivemeans. 2. A television projection head as defined in claim 1 and furthercomprising:

means for moving said; phosphor coated screen:

means at a predetermined rate which will prevent damage to said phosphorcoated screen means by repetitive single line sweeps by said electronbeams.

3. A television projection head asdefined in claim 2,

and wherein:

said envelope is substantially cylindrical in shape,

said axis being the central axis thereof; and

said phosphor coated screen means comprises a transparent disc lying ina plane normal to said axis of said envelope and having an electron beamex-.

citable phosphor coating facing said electron guns.

4. A television projection head as defined in claim 3,

and wherein:

said means for moving said phosphor coated screen means comprises ashaft extending coaxial with the axis of said envelope and supportingsaid disc; and bearing means for supporting said shaft for rotation ofsaid disc about said axis.

5. A television projection head as defined in claim 4,

and wherein:

said means for moving-said phosphor coated screen means furthercomprises electric motor means supported by said envelope and coupled tosaid shaft.

6. A television projection head as defined in claim 5,

pled to said envelope.

1. A television projection head for providing 360* panoramic projectionon a surrounding projection screen, said head comprising: frame means;an envelope mounted for rotation with respect to said frame means abouta vertical axis; drive means for rotating said envelope; a plurality ofelectron guns disposed within said envelope in equispaced relation aboutsaid axis and with their principal axis parallel thereto; phosphorcoated screen means disposed in the path of electron beams from saidguns; a plurality of reflecting means, each disposed to reflect radiallyoutwardly light emitted by said phosphor coated screen means whenscanned by the electron beam from a respective one of said guns; and aplurality of projection lens means, each associated with one of saidreflecting means, for focusing said reflected light upon a screenwhereby radial single line scans of said phosphor coated screen means byeach of said guns will produce a raster of substantially vertical linescans on said projection screen as said head is rotated by said drivemeans.
 2. A television projection head as defined in claim 1 and furthercomprising: means for moving said phosphor coated screen means at apredetermined rate which will prevent damage to said phosphor coatedscreen means by repetitive single line sweeps by said electron beams. 3.A television projection head as defined in claim 2, and wherein: SAIDenvelope is substantially cylindrical in shape, said axis being thecentral axis thereof; and said phosphor coated screen means comprises atransparent disc lying in a plane normal to said axis of said envelopeand having an electron beam excitable phosphor coating facing saidelectron guns.
 4. A television projection head as defined in claim 3,and wherein: said means for moving said phosphor coated screen meanscomprises a shaft extending coaxial with the axis of said envelope andsupporting said disc; and bearing means for supporting said shaft forrotation of said disc about said axis.
 5. A television projection headas defined in claim 4, and wherein: said means for moving said phosphorcoated screen means further comprises electric motor means supported bysaid envelope and coupled to said shaft.
 6. A television projection headas defined in claim 5, and further comprising: slip ring means mountedon said envelope for rotation therewith; brush means mounted on saidframe means for cooperation with said slip rings; and conductor meansconnecting said slip ring means to said electron guns and to saidelectric motor means for moving said phosphor coated screen means.
 7. Atelevision projection head as defined in claim 6, and wherein: saiddrive means for rotating said envelope comprises an electric motormounted on said frame and coupled to said envelope.